AU2023203764A1 - Optical fiber with an immediate fluorine cladding - Google Patents

Abstract

The present disclosure relates to an optical fiber (100) comprising a core (102) up-doped with an up-dopant such as Germanium (Ge), a cladding (104) that has inner and outer claddings (108, 110). In particular, the inner cladding (108) is down doped with a down dopant and is disposed adjacent to the core (102) and the outer cladding (110) is at least one of, undoped and down doped. Moreover, the optical fiber (100) has (i) a Mode Field Diameter (MFD) in a range of 9.5 pm to 13.0 pm and (ii) a Cable Cut off of less than 1530 nm.

Description

OPTICAL FIBER WITH AN IMMEDIATE FLUORINE CLADDING TECHNICAL FIELD

[0001] Embodiments of the present disclosure relate to the field of optical fiber

communications, and more particularly to an optical fiber with an immediate fluorine

cladding positioned adjacent to the core.

[0002] This application claims the benefit of Indian Application No.202211077232 titled

"OPTICAL FIBER WITH AN IMMEDIATE FLUORINE CLADDING" filed by the applicant

on December 30, 2022, which is incorporated herein by reference in its entirety.

Background Art

[0003] Optical fiber as optical communication network underlying transport physical

media, can direct body to the improvement of its Transmission system performance Now

in the improvement of OSNR (OSNR).The loss of optical fiber and nonlinear effect are

limitation high-speed high capacity fiber optic communication systems. The key factor of

system OSNR. Proved by correlative study, increase the effective area (A of optical

fibereff), can not only be added to fine light Power, can also effectively reduce nonlinear

effect. So increasing optical fiber effective area, it is to overcome fiber loss to reduce

fiber loss with the main path of the two restraining factors of nonlinear effect.

[0004] Telecommunication systems for underground and undersea applications, require

optical fibers that can transmit signals to longer distances without any degradation.

However, the optical fiber attributes such as attenuation and bend loss can contribute to

some degradation of the signals transmitted through the optical fiber.

[00051 Single mode fibers of G.652.D/G657A2 generally face major challenges in 400G

transmission in territorial long haul communication systems due to non-linear effects,

mainly in submarine application. Single mode fibers of G654E/G654C is specifically

characterized by cut-off shifted, low attenuation, low latency, higher Optical Signal to

Noise Ratio (OSNR) as compared to G.652.D/G657A2. Also, single mode fibers of

G654E have large effective area and large Mode Field Diameter (MFD) as compared to

G.652.D/G657A2.

[0006] The main component of telecommunication optical fiber is silica.In preform

manufacturing process, typically by mixing dioxy Changing germanium and improve the

refractive index of sandwich layer, and mix fluorine element reduces cladding index.By

the effort of 40 years, prefabricated rods and light Fine manufacturing process has

reached ultimate attainment.In addition to the Intrinsic Gettering of silica, the absorption

and scattering of the germanium dioxide that adulterates It is the main source of

telecommunication optical fiber decay, therefore the content for reducing sandwich layer

germanium dioxide is the Main way for reducing optical fiber attenuation. Existing typical

case is G.654 in Single Mode Fiber Design, although the refractive index of its sandwich

layer and the content of germanium dioxide are substantially less than typical case G.652

optical fiber, but its mode field diameter, cutoff wavelength AccThe further of sandwich

layer germanium dioxide doping is limited with bending loss Decline.

[0007] Prior art reference CN106772788A discloses a kind of cut off wavelength

displacement single-mode fiber having a sandwich layer, an inner cladding for coating

successively, a depressed cladding, a middle covering and a surrounding layer. The

single mode fiber provides properties such as low decay, large effective area and low

bend loss, and can realize the controllability of fiber cut off wavelength.

[0008] Another prior art referenceUS20170003445Al discloses an optical fiber with

large effective area, low bending loss and low attenuation. The optical fiber includes a

core, an inner cladding region, and an outer cladding region. The core region includes a

spatially uniform up-dopant to minimize low Rayleigh scattering and a relative refractive index and radius configured to provide a large effective area. The inner cladding region features a large trench volume to minimize bending loss.

[oo9] Yet another prior art reference US20130071080A1 discloses a trench-assisted

optical fiber, optimized for figure-of-merit (FOM) performance, having a core region

having a longitudinal axis, a shelf region surrounding said core region, a cladding region

surrounding said shelf region, said core and shelf and cladding regions configured to

support and guide the propagation of signal light in a fundamental transverse mode in

said core and shelf regions in the direction of said axis, the cladding region including an

inner trench and an outer trench.

[0010] Therefore, in the light of the above-stated discussion, there is a need to provide

a technical solution that overcomes the aforementioned problems of the traditional single

mode optical fibers by providing an optical fiber with higher cut-off wavelength, large

effective area, large Mode Field Diameter (MFD), low attenuation, low latency, and higher

Optical Signal to Noise Ratio (OSNR).

SUMMARY OF THE DISCLOSURE

[0011] Embodiments of the present disclosure provide

[0012] According to the first aspect of the present disclosure, an optical fiber comprising

a core that is up doped with an up dopant; the up dopant is Germanium (Ge) and a

cladding having inner and outer claddings. The inner cladding is down doped with a down

dopant and disposed adjacent to the core. The outer cladding is either undoped or down

doped.

[0013] In accordance with an embodiment of the present disclosure, the optical fiber has

(i) a Mode Field Diameter (MFD) in a range of 9.5 pm to 13.0 pm and (ii) a Cable Cut off

of less than 1530 nm.

[0014] According to the second aspect of the present disclosure, the core has a core

radius R1 in a range of 4.5 micrometres (pm) to 6.5 pm, the inner cladding has an inner cladding radius R2 in a range of 22 pm to 25 pm, and the outer cladding has an outer cladding radius R3 in a range of 62.15 pm to 62.85 pm.

[0015] In accordance with an embodiment of the present disclosure, the outer cladding is

made of pure silica. Further, the outer cladding has traces of down dopant near an inner

cladding-outer cladding interface.

[0016] In accordance with an embodiment of the present disclosure, the core has traces

of the down dopant in concentrations less than 2500 parts per million (ppm).

[0017] According to the third aspect of the present disclosure, the down dopant is at least

one of Chlorine (CI) and Fluorine (F).

[0018] According to the fourth aspect of the present disclosure, the inner cladding has a

trench layer defined by a non-step single trench shape. The end of the inner cladding

adjacent to the core is deeper than the end of the core adjacent to the inner cladding in

the trench layer .

[0019] According to the fifth aspect of the present disclosure, a ratio of the core volume

to the trench volume is in a range of 0.082 to 0.11. The core has a core volume in a

range of 5% pm 2 to 5.5% pm2, and the trench layer has a trench volume in a range of

48% pm 2 to 55% pm 2 .

[0020] According to the sixth aspect of the present disclosure, when the outer cladding is

undoped, macro bend loss of the optical fiber at a wavelength of 1625 nm, a bend

diameter of 60 millimeters (mm), 100 turns of the optical fiber is less than 0.5 Decibel

(dB).And, when the outer cladding is down doped, a macro bend loss of the optical fiber

at a wavelength of 1625 nm, a bend diameter of 60 mm, 100 turns of the optical fiber is

less than 0.1 dB.

[0021] According to the seventh aspect of the present disclosure, attenuation of the

optical fiber is less than 0.17 dB/KM. And, the total profile volume of the optical fiber is

in a range of 50% pm 2 to 60.50% pm 2 .

[0022] These and other aspects herein will be better appreciated and understood when

considered in conjunction with the following description and the accompanying drawings.

It should be understood, however, that the following descriptions are given by way of

illustration and not of limitation. Many changes and modifications is made within the

scope of the disclosure herein without departing from the spirit thereof.

BRIEF DESCRIPTION OF DRAWINGS

[0023] To describe the technical solutions in the embodiments of the present disclosure

or in the prior art more clearly, the following briefly describes the accompanying drawings

required for describing the embodiments or the prior art. Apparently, the accompanying

drawings in the following description merely show some embodiments of the present

disclosure, and a person of ordinary skill in the art can derive other implementations from

these accompanying drawings without creative efforts. All of the embodiments or the

implementations shall fall within the protection scope of the present disclosure.

[0024] Fig. 1 is a pictorial snapshot illustrating a cross-sectional view of an optical fiber

in accordance with an embodiment of the present disclosure;

[0025] Fig. 2A is a graphical representation illustrating a Refractive Index (RI) profile of

the optical fiber with an outer cladding being down doped with a down dopant in

accordance with an embodiment of the present disclosure;

[0026] Fig. 2B is an enlarged sectional view of the graph illustrating a RI profile of a core

of the optical fiber with the outer cladding being down doped with the down dopant in

accordance with an embodiment of the present disclosure;

[0027] Fig. 2C is another enlarged sectional view of the graph illustrating RI profile of an

inner cladding of the optical fiber with the outer cladding being down doped with the down

dopant in accordance with an embodiment of the present disclosure;

[0028] Fig. 2D is another enlarged sectional view of the graph illustrating RI profile of the

outer cladding of the optical fiber with the outer cladding being down doped with the

down dopant in accordance with an embodiment of the present disclosure;

[0029] Fig. 2E is an enlarged sectional view of the graph illustrating a RI profile of an inner

cladding-outer cladding interface of the optical fiber with the outer cladding being down

doped with the down dopant in accordance with an embodiment of the present

disclosure;

[0030] Fig. 3A is a graphical representation illustrating a RI profile of the optical fiber with

the outer cladding being undoped in accordance with an embodiment of the present

disclosure;

[0031] Fig. 3B is an enlarged sectional view of the graph illustrating a RI profile of a core

of the optical fiber with the outer cladding being undoped in accordance with an

embodiment of the present disclosure;

[0032] Fig. 3C is an enlarged sectional view of the graph of illustrating a RI profile of an

inner cladding of the optical fiber with the outer cladding being undoped in accordance

with an embodiment of the present disclosure;

[0033] Fig. 3D is an enlarged sectional view of the graph illustrating a RI profile of the

outer cladding of the optical fiber with the outer cladding being undoped in accordance

with an embodiment of the present disclosure;

[0034] Fig. 3E is an enlarged sectional view of the graph illustrating a RI profile of an inner

cladding-outer cladding interface of the optical fiber with the outer cladding being

undoped in accordance with an embodiment of the present disclosure.

[0035] The optical fiber illustrated in the accompanying drawings, which like reference

letters indicate corresponding parts in the various figures. It should be noted that the

accompanying figure is intended to present illustrations of exemplary embodiments of

the present disclosure. This figure is not intended to limit the scope of the present disclosure. It should also be noted that the accompanying figure is not necessarily drawn to scale.

DESCRIPTION OF EMBODIMENTS

[0036] Those skilled in the art will be aware that the present disclosure is subject to

variations and modifications other than those specifically described. It is to be

understood that the present disclosure includes all such variations and modifications.

The disclosure also includes all such steps, features, compositions and compounds

referred to or indicated in this specification, individually or collectively, and any and all

combinations of any or more of such steps or features.

Definitions:

[0037] For convenience, before further description of the present disclosure, certain terms

employed in the specification, and examples are collected here. These definitions should

be read in the light of the remainder of the disclosure and understood as by a person of

skill in the art. The terms used herein have the meanings recognized and known to those

of skill in the art, however, for convenience and completeness, particular terms and their

meanings are set forth below.

[0038] The articles "a", "an" and "the" are used to refer to one or to more than one (i.e.,

to at least one) of the grammatical object of the article.

[0039] The terms "comprise" and "comprising" are used in the inclusive, open sense,

meaning that additional elements is included. It is not intended to be construed as

"consists of only". Throughout this specification, unless the context requires otherwise

the word "comprise", and variations such as "comprises" and "comprising", will be

understood to imply the inclusion of a stated element or step or group of element or steps

but not the exclusion of any other element or step or group of element or steps.

[0040] The term "including" is used to mean "including but not limited to". "Including" and

"including but not limited to" are used interchangeably.

[0041] Optical fiber refers to a medium associated with the transmission of information

over long distances in the form of light pulses. The optical fiber uses light to transmit

voice and data communications over long distances when encapsulated in a

jacket/sheath. The optical fiber is of ITU.T G.657.A2 category. Alternatively, the optical

fiber is of ITU.T G.657.A1 or G.657.B3 or G.652.D or other suitable categories. The ITU.T

stands for International Telecommunication Union-Telecommunication Standardization

Sector, is one of the three sectors of the ITU. The ITU is the United Nations specialized

agency in the field of telecommunications and is responsible for studying technical,

operating and tariff questions and issuing Recommendations on them with a view to

standardizing telecommunications on a worldwide basis.

[0042] The term "core" of an optical fiber is referred to as the inner most cylindrical

structure present in the center of the optical fiber, that is configured to guide the light rays

inside the optical fiber.

[0043] The term "cladding" of an optical fiber is referred to as one or more layered

structure covering the core of an optical fiber from the outside, that is configured to

possess a lower refractive index than the refractive index of the core to facilitate total

internal reflection of light rays inside the optical fiber. Further, the cladding of the optical

fiber include an inner cladding layer coupled to the outer surface of the core of the optical

fiber and an outer cladding layer coupled to the inner cladding from the outside.

[0044] The term "inner cladding" of the optical fiber is referred to as a layer surrounding

to the core of the optical fiber.

[0045] The term "outer cladding" of the optical fiber is referred to as a layer surrounding

the inner cladding of the optical fiber.

[0046] The term "trench layer" referred to as a down doped region with a higher down

dopant concentration to decrease the refractive index of the down doped region with

respect to pure silica and increase the relative refractive index of the core region.

[0047] The term "refractive index" is referred to as the measure of change of speed of

light from one medium to another and is particularly measured in reference to speed of

light in vacuum. More specifically, the refractive index facilitates measurement of bending

of light from one medium to another medium.

[0048] The term "relative refractive index" is referred to as the ratio of refractive index of

one medium to the refractive index of other medium.

[0049] The term "refractive index profile" of the optical fiber is referred to as the distribution

of refractive indexes in the optical fiber from the core to the outmost cladding layer of the

optical fiber. Based on the refractive index profile, the optical fiber is configured as a step

index fiber. The refractive index of the core of the optical fiber is constant throughout the

fiber and is higher than the refractive index of the cladding. Further, the optical fiber is

configured as a graded index fiber, wherein the refractive index of the core gradually

varies as a function of the radial distance from the center of the core.

[0050] The term "Mode Field Diameter (MFD)" refers to the size of the light-carrying

portion of the optical fiber. For single-mode optical fibers, this region includes the optical

fiber core as well as a small portion of the surrounding cladding glass of the optical fiber.

The selection of desired MFD helps to describe the size of the light-carrying portion of

the optical fiber.

[0051] The term "macro bend loss" refers to losses induced in bends around mandrels (or

corners in installations), generally more at the cable level or for fibers. The macro bend

loss occurs when the fiber cable is subjected to a significant amount of bending above a

critical value of curvature. The macro bend loss is also called as large radius loss.

[0052] The term "cable cut-off wavelength" refers to a wavelength above which a single

mode fiber will support and propagate only one mode of light. The optical fiber transmits

a single mode of optical signal above a pre-defined cut-off wavelength known as cable

cut-off wavelength.

[0053] The term "effective area" refers to an optical effective area. A large effective area

is always preferred in the optical fiber for an efficient optical transmission.

[0054] The term "latency" is referred to as a time delay that occurs when transmitting a

light signal over a length of the optical fiber.

[0055] The term "attenuation" is referred to as the reduction in power of a light signal as

it is transmitted. Specifically, the attenuation is caused by passive media components

such as cables, cable splices, and connectors.

[0056] The term "Optical Signal to Noise Ratio (OSNR)" is referred to as the ratio of signal

power to noise power, over a specific spectral bandwidth, at any point in an optical link.

[0057] The term "core peak" is referred to as the maximum refractive index value of the

core of the optical fiber.

[0058] The term "up-doping" is referred to as adding doping materials to facilitate increase

in the refractive index of a particular layer or part of optical fiber. The materials configured

to facilitate up-doping are known as up-dopants.

[0059] The term "down-doping" is referred to as adding doping materials to facilitate

decrease in the refractive index of a particular layer or part of optical fiber. The materials

configured to facilitate down-doping are known as down-dopants.

[0060] The term "undoped" (or unintentionally doped) means that a region of the optical

fiber contains a dopant not intentionally added to the region during fabrication, but the

term does not exclude low levels of background doping that is inherently incorporated

during the fabrication process. Such background doping levels are low in that they have

an insignificant effect on the refractive index of the undoped region.

[0061] The optical fiber 100 is complied with the G.654.E standard issued by International

Telecommunications Union - Telecommunications Sector (ITU-T), that is latest revision

of "ITU-T Recommendation G.654 - Characteristic of a Cut-Off Shifted Single-mode

Optical Fiber and Cable". The former revisions of ITU-T G.654 standard include G.654.A,

G.654.B, G.654.C and G.654.D that describes optical fibers typically used in submarine

applications.

[0062] Fig.1 illustrates a cross-sectional view of an optical fiber 100. In particular, the

optical fiber 100 is Outside Vapor Deposition (OVD) manufactured optical fiber having

an immediate fluorine cladding that induces G654C/E properties in the optical fiber 100.

In particular, the optical fiber 100 is a G.654.E fiber which is a cut-off wavelength shift

single-mode optical fiber.

[0063] The optical fiber 100 have a core 102 and a cladding 104, a central axis 106. In

particular, the core 102 and the cladding 104 are arranged along the central axis 106

running longitudinally, i.e., generally concentric to the central axis 106. Moreover, the

cladding 104 includes an inner cladding 108 and an outer cladding 110.

[0064] In accordance with an embodiment, of the present disclosure, the optical fiber 100

have a Refractive Index (RI) profile generated by virtue of the core 102 being up doped

with an up dopant, the inner cladding 108 being down doped with a down dopant, and

the outer cladding 110 being one of, undoped (i.e., made up of pure silica) and down

doped with a down dopant.

[00651 In accordance with an embodiment, of the present disclosure, the core 102 is a

cylindrical fiber that run along a length of the optical fiber 100 and is configured to guide

an optical signal. In particular, the core 102 is a confinement region of the optical fiber

100. Moreover, the core 102 is made up of a material selected from at least one of, a

pure silica glass, Silicon tetrachloride (SiCl4), Germanium tetrachloride (GeCl4), and the

like. Further, the core 102 is made up of a silica glass doped with the up dopant.

[0066] Furthermore, the core 102 is up-doped with the up-dopant that increases net

refractive index of the optical fiber 100 to control macro bend losses., the up dopant is

Germanium (Ge). The up dopant Germanium (Ge) is preferred over other up dopant.

Aspects of the present disclosure are intended to include and/or otherwise cover any type of the up dopant for the core 102, without deviating from the scope of the present disclosure.

[0067] In alternate aspects of the present disclosure, the core 102 have traces of chlorine

(CI) and fluorine (F). Particularly, concentrations of Cl and F in the core 102 is less than

2500 parts per million (ppm) and 1500 ppm, respectively. Moreover, the traces of chlorine

(CI) and fluorine (F) are used to up dope the core 102 as the chlorine (CI) and the fluorine

(F) facilitates in reduction of stress in an optical fiber preform and hence in the optical

fiber 100. Further, the traces of the chlorine (CI) and the fluorine (F) act as a core

viscosity reduction agent such that the core 102 becomes softer (i.e., easy to flow to

provide relaxation and ease in releasing of stress from the hot optical fiber preform).

[0068] In accordance with an embodiment of the present disclosure, the core 102 has a

core radius R1 in a range of 4.5 micrometres (pm) to 6.5 pm. The core volume that is

defined as a volume acquired by the core 102 with respect to the core radius R1. The

core volume have a magnitude in micrometres square (pm 2) that is determined by the

following equation:

= R A(r) rdrl

[0069] In some aspects of the present disclosure, the magnitude of the core volume of

the core 102 as determined by the above equation is in a range of 5% pm 2 to 5.5% pm 2 .

In an exemplary example, the core volume of the core 102 is 5.25% pm2.

[0070] In accordance with an embodiment of the present disclosure, the cladding 104

having the inner cladding 108 and the outer cladding 110 is a layer made up of a material

having a lower refractive index and is in immediate contact with the core 102 made up of a material of higher refractive index. In particular, the inner cladding 108 surrounds the core 102. Moreover, the inner cladding 108 is disposed adjacent to the core 102.

[0071] In some aspects of the present disclosure, an end of the inner cladding 108 that is

adjacent to the core 102 (i.e., at an intersection of the core 102 and the inner cladding

108) is substantially deeper when compared to an end of the core 102 adjacent to the

inner cladding 108 (i.e., at an intersection of the core 102 and the inner cladding 108).

In particular, the deeper end of the inner cladding 108 at the intersection of the core 102

and the inner cladding 108 forms a trench layer 108a that has a non-step single trench

shape. Moreover, the non-step single trench shape is preferred over stepped trench

because the manufacturing process of the optical fiber with non-step trench is less

complex and less time consuming as compared to the manufacturing process of the

optical fiber comprising stepped trench.

[0072] In accordance with an embodiment of the present disclosure, the trench layer 108a

has a trench radius R2 (i.e., inner cladding radius) in a range of 22 pm to 25 pm.

[0073] In some aspects of the present disclosure, the trench layer 108a have a trench

volume that is defined as a volume acquired by region between the core radius R1 and

the trench radius R2. The trench volume have a magnitude in pm 2 that is determined by

the following equation:

=-fA(r)rdr

[0074] In accordance with an embodiment of the present disclosure, the magnitude of the

trench volume of the trench layer (i.e., the inner cladding 108) determined by the above 2 equation is in a range of 48% pm to 55% pm 2 . In one exemplary example, the trench

volume of the trench layer 108a is equal to 48.59% pm 2 .

[0075] In some aspects of the present disclosure, the trench layer 108a have a trench

delta that is in a range of 0.22% to 0.32%. Preferably, the trench layer have the trench

delta of 0.24%. The trench delta is determined by the following equation:

n1 2 - n2 2 A (%0) = 2 * n1 2 100

Where, A is trench delta,

n1 is refractive index of trench layer,

n2 is refractive index of pure silica.

[0076] In an exemplary example, refractive index n1 of the trench layer 108a is 1.44332

and refractive index of pure silica is 1.44692, the trench delta determined using above

equation is 0.25%.

[0077] In accordance with an embodiment of the present disclosure, the inner cladding

108 is made up of a material such as, but not limited to, a silica glass. In some alternate

aspects of the present disclosure, the inner cladding 108 is made up of a combination of

Silicon tetrachloride (SiC4) and Cl. Particularly, the inner cladding 108 is made up of a

silica glass doped with the down dopant. Moreover, the inner cladding 108 down doped

with the down dopant decrease values of net refractive index of the inner cladding 108

controls macro bend losses in the optical fiber 100.

[0078] The outer cladding 110 surround the inner cladding 108 and is made up of a

material such as but not limited to, a silica glass. In some aspects of the present

disclosure, the outer cladding 110 is made up of a silica glass that is undoped, or down

doped with a down dopant. The down dopant used to dope the outer cladding 110 is

similar to the down dopant used to down dope the inner cladding 108. Alternatively, the

down dopant used to dope the outer cladding 110 is different than the down dopant used to down dope the inner cladding 108. The outer cladding 110 have an outer cladding radius R3 that is in a range of 62.15 pm to 62.85 pm.

[0079] In accordance with an embodiment of the present disclosure, the optical fiber 100

have a total profile volume. The total profile volume have a magnitude in pm 2 that is

determined by the following equation:

= fR A (r)rdr

[0080] In some aspects of the present disclosure, the magnitude of the profile volume as

determined by the above equation is in a range of 50% pm 2 to 60.50% pm 2. The profile

volume is determined by surface integrating the relative refractive index as a function of

radial change. In one example, the total profile volume is determined with integration

limits of core center to outer cladding radius R3 (0 to 62.5 pm).

[0081] In accordance with an embodiment of the present disclosure, the trench volume of

the trench layer 108a is in a range of 45.00% pm 2 to 55.00% pm 2. In some aspects of

the present disclosure, the trench layer 108a have a trench delta that is in a range of

0.22% to 0.32

[0082] In accordance with an embodiment of the present disclosure, a ratio of the core

volume to the trench volume is in a range of 0.082% to 0.11%. The minimum value in

the range of the ratio of the core volume to the trench volume is determined by dividing

the minimum value of the core volume by the maximum value of the trench volume. For

example, the minimum value of core volume is 5% pm 2 and the maximum value of the

trench volume is 55.00% pm2 , the minimum value of the ratio of the core volume to the

trench volume is 0.09%. The maximum value in the range of the ratio of the core volume

to the trench volume is determined by dividing the maximum value of the core volume

by the minimum value of the trench volume. For example, the maximum value of core volume is 5.5% pm 2 and the minimum value of the trench volume is 45.00% pm 2, the maximum value of the ratio of the core volume to the trench volume is 0.12%.

[0083] In accordance with an embodiment of the present disclosure, the core volume in

the range of 5% pm 2 to 5.5% pm 2, the trench volume in the range of 45% pm 2 to 55%

pm2 , and the profile volume in the range of 50% pm 2 to 60.50% pm 2 facilitate to get

G654E/C parameters in the optical fiber 100. The G654E/C parameters is, but not limited

to, MFD at 1550 nm in range of 9.5 to 13.0, Cable Cut off of less than 1530 nm,

Attenuation at 1550 nm of less than 0.17 dB/Km, Dispersion in range of about 17

picosecond per nanometer-kilometer (ps/(nm.Km)) to 23 ps/(nm.Km) at wavelength of

about 1550 nm. When the outer cladding 110 is undoped, a Macro bend loss at a

wavelength of 1625 nm, 60 mm diameter and 100 turns of the optical fiber 100 is less

than 0.5 Decibel (dB). When the outer cladding 110 is down doped, a Macro bend loss

at a wavelength of 1625 nm, 60 mm diameter and 100 turns of the optical fiber is less

than 0.1 dB.

[0084] In an exemplary scenario, when the optical fiber 100 has theoutercladding 110

that is down doped with the down dopant (i.e., F), then thecore radius R1 is in a range

of 5.5 pm to 6.5 pm, a maximum refractive index Almax of the core 102 is in a range of

0.38% to 0.45%. Particularly, the core radius R1 is 5.92 pm, the maximum refractive

index Almax of the core 102 is 0.41%. The inner cladding radius R2 is in a range of 22

pm to 25 pm, a maximum refractive index A2max of the inner cladding 108 is in a range

of 0.26% to 0.32%. Moreover, the inner cladding radius R2 is 22.5 pm, the maximum

refractive index A2max of the inner cladding 108 is 0.28%. The outer cladding radius R3

is in a range of 62.15 pm to 62.85 pm, a maximum refractive index A3max of the outer

cladding 110 is in a range of 0.10% to 0.20%. Further, the outer cladding radius R3 is

62.5 pm, the maximum refractive index A3max of the outer cladding 110 is 0.15%. The

core volume is in a range of 5% pm 2 to 5.5% pm 2, the trench volume is in a range of 48% pm 2 to 55% pm2, and the total profile volume is in a range of 53% pm 2 to 60.5% pm 2. In one example, the core volume is 5.01% pm 2, the trench volume is 49.15% pm 2, and the total profile volume is 54.16% pm 2

.

[0085] In another exemplary scenario, when the optical fiber 100 has the outer cladding

110 that is undoped, the core radius R1 is in a range of 4.5 pm to 5.5 pm, the maximum

refractive index Almax of the core 102 is in a range of 0.38% to 0.45%. In particular, the

core radius R1 is 5 pm and the maximum refractive index Almax of the core 102 is

0.42%. The inner cladding radius R2 is in a range of 22 pm to 25 pm, the maximum

refractive index A2max of the inner cladding 108 is in a range of 0.22% to 0.26%.

Moreover, the cladding radius R2 is 23.5 pm and the maximum refractive index A2max

of the inner cladding 108 is 0.24%. The outer cladding radius R3 is in a range of 62.15

pm to 62.85 pm, the maximum refractive index A3max of the outer cladding 110 is in a

range of -0.05% to 0.05%. Further, the cladding radius R3 is 62.5 pm and the maximum

refractive index A3max of the outer cladding 110 is 0. The core volume is in a range of

% pm 2 to 5.5% pm2, the trench volume is in a range of 45% pm 2 to 50% pm 2, and the

total profile volume is in a range of 50% pm 2 to 55.5% pm 2 . In one example, the core

volume is 5.25% pm 2, the trench volume is 48.59% pm 2, and the total profile volume is

53.84% pm 2 .

[0086] Fig.2A illustrates a graph 200 illustrating a Refractive Index (RI) profile of the

optical fiber 100 with the outer cladding 110 being down doped with the down dopant.

The graph 200 is a radius versus relative refractive index graph such that an x-axis of

the graph 200 represents values of the radius R1, the radius R2, and the radius R3 of

the core 102, the inner cladding 108 (i.e., the trench layer 108a), and the outer cladding

110, respectively, and a y-axis of the graph 200 represents values of the refractive index

Al, the refractive index A2, and the refractive index A3 of the core 102, the inner cladding

108 (i.e., the trench layer 108a), and the outer cladding 110, respectively. The graph 200 has a curve 202 that represent the RI profile of the optical fiber 100. As illustrated the core 102 being up doped with the up dopant, the inner cladding 108 being down doped with the down dopant, and the down doped outer cladding 110 generates the RI profile.

Moreover, the core 102 defines a core region such that the refractive index Al of the

core 102 is realized in the core region (i.e., within the radius R1 of the core 102). Further,

the inner cladding 108 (i.e., the trench layer 108a) defines a trench region such that the

refractive index A2 of the inner cladding 108 (i.e., the trench layer 108a) is realized in

the trench region (i.e., within the radius R2 of the inner cladding 108). Furthermore, the

outer cladding 110 define an outer cladding region such that the refractive index A3 of

the outer cladding 110 is realized in the outer cladding region (i.e., within the radius R3

of the outer cladding 110).

[0087] The curve 202 illustrates a value of the refractive index Al is maximum at a core

peak 204 in the core region that is up doped by the up dopant (i.e., GE). Further, the

curve 202 transitions from the core region to the trench region which is down doped with

the down dopant (i.e., F) such that the curve 202 dips in the trench region (i.e., the region

defined by R2 - R1). Specifically, the curve 202 illustrates that a value of the refractive

index A2 is minimum at an inner cladding dip point 206 in the trench region that is down

doped by the down dopant (i.e., F).

[0088] The curve 202 further transitions from the trench region to the outer cladding region

defined by the outer cladding 110 that is down doped with the down dopant such that the

curve 202 peaks to an outer cladding peak 208a at an inner cladding-outer cladding

interface 208b that is lesser than the core peak 204. Further, the curve 202 transitions

from the core region to the trench region and further from the trench region to the outer

cladding region (i.e., the region defined by R3 - R2) thus generating the RI profile that

is defined by the core peak 204 and the outer cladding peak 208a at the inner cladding

outer cladding interface 208b.

[0089] The graph 200 has a straight line 210 that defines the refractive index of pure silica.

Further, the curve 202 dips after the inner cladding-outer cladding interface 208b that

defines that the refractive index A3 of the outer cladding 110 decrease gradually and is

less than the refractive index of pure silica which is due to the fact the outer cladding 110

is down doped using the down dopant.

[0090] Fig. 2B is an enlarged sectional view of the graph 200 illustrating a RI profile of the

core 102 of the optical fiber 100 with the outer cladding 110 being down doped with the

down dopant. The core 102 defines the core region such that the refractive index Al of

the core 102 is realized in the core region (i.e., within the radius R1 of the core 102).

Moreover, the curve 202 illustrates that the value of the refractive index Al is maximum

at the core peak 204 in the core region that is up doped by the up dopant (i.e., GE).

[0091] In one exemplary example, the core volume of the core 102 is 5.25% pm2. In

particular, the core volume is determined by surface integrating the relative refractive

index as a function of radial change. In another example, the core volume is determined

with integration limits of core center to core radius R1 (0 to 5.35 pm).

[0092] Further, the curve 202 transitions from the core region to the trench region which

is down doped with the down dopant (i.e., F) such that the curve 202 dips in the trench

region (i.e., the region defined by R2 - R1).

[0093] Fig. 2C is another enlarged sectional view of the graph 200 illustrating a RI profile

of the inner cladding 108 of the optical fiber 100 with the outer cladding 110 being down

doped with the down dopant. The inner cladding 108 (i.e., the trench layer 108a) defines

the trench region such that the refractive index A2 of the inner cladding 108 (i.e., the

trench layer 108a) is realized in the trench region (i.e., within the radius R2 of the inner

cladding 108). The deeper end of the inner cladding 108 at the intersection of the core

102 and the inner cladding 108 form a trench layer 108a that has a non-step single trench

shape as illustrated by the curve 202. Moreover, the non-step single trench shape is preferred over stepped trench because the manufacturing process of the optical fiber with non-step trench is less complex and less time consuming as compared to the manufacturing process of the optical fiber comprising stepped trench. Further, the curve

202 illustrates that the value of the refractive index A2 is minimum at the inner cladding

dip point 206 in the trench region that is down doped by the down dopant (i.e., F). The

non-step trench shape of the trench layer 108a comprising only one dip point 206.

[0094] Fig.2D is another enlarged sectional view of the graph 200 illustrating a RI profile

of the outer cladding 110 of the optical fiber 100 with the outer cladding 110 being down

doped with the down dopant. In particular, the outer cladding 110 define the outer

cladding region such that the refractive index A3 of the outer cladding 110 in the outer

cladding region (i.e., within the radius R3 of the outer cladding 110). Moreover, the curve

202 further transitions from the trench region to the outer cladding region defined by the

outer cladding 110 that is down doped with the down dopant such that the curve 202

peaks to an outer cladding peak 208a at an inner cladding-outer cladding interface 208b

that is lesser than the core peak 204. Further, the curve 202 transitions from the core

region to the trench region and further from the trench region to the outer cladding region

(i.e., the region defined by R3 - R2) thus generating the RI profile that is defined by the

core peak 204 and the outer cladding peak 208a at the inner cladding-outer cladding

interface 208b. The graph 200 has the straight line 210 that defines the refractive index

of pure silica. As illustrated, the curve 202 dips after the inner cladding-outer cladding

interface 208b that defines that the refractive index A3 of the outer cladding 110 decrease

gradually and is less than the refractive index of pure silica which is due to the fact the

outer cladding 110 is down doped using the down dopant.

[0095] Fig. 2E is an enlarged sectional view illustrating a RI profile of the inner cladding

outer cladding interface 208b of the optical fiber 100 with the outer cladding 110 being

down doped with the down dopant. The curve 202 transitions from the trench region to the outer cladding region defined by the outer cladding 110 that is down doped with the down dopant such that the curve 202 peaks to the outer cladding peak 208a at the inner cladding-outer cladding interface 208b that is lesser than the core peak 204. Moreover, the curve 202 transitions from the core region to the trench region and further from the trench region to the outer cladding region (i.e., the region defined by R3 - R2) thus generating the RI profile that is defined by the core peak 204 and the outer cladding peak

208a at the inner cladding-outer cladding interface 208b. The graph 200 further has a

straight line 210 that defines the refractive index of pure silica.

[0096] Fig. 3A is a graph 300 representing a RI profile of the optical fiber 100 with the

outer cladding 110 being undoped. The graph 300 is a radius versus relative refractive

index graph such that an x-axis of the graph 300 represents values of the radius R1, the

radius R2, and the radius R3 of the core 102, the inner cladding 108 (i.e., the trench

layer 108a), and the outer cladding 110, respectively, and a y-axis of the graph 200

represents values of the refractive index Al, the refractive index A2, and the refractive

index A3 of the core 102, the inner cladding 108 (i.e., the trench layer 108a), and the

outer cladding 110. The graph 300 has a curve 302 that represent the RI profile of the

optical fiber 100. Moreover, the core 102 being up doped with the up dopant, the inner

cladding 108 being down doped with the down dopant, and the undoped outer cladding

110 generates the RI profile. Further, the core 102 defines a core region such that the

refractive index Al of the core 102 is realized in the core region (i.e., within the radius

R1 of the core 102). Furthermore, the inner cladding 108 (i.e., the trench layer 108a)

defines a trench region such that the refractive index A2 of the inner cladding 108 (i.e.,

the trench layer 108a) is realized in the trench region (i.e., within the radius R2 of the

inner cladding 108). The outer cladding 110 define an outer cladding region such that

the refractive index A3 of the outer cladding 110 is realized in the outer cladding region

(i.e., within the radius R3 of the outer cladding 110).

[0097] The curve 302 illustrates a value of the refractive index Al is maximum at a core

peak 304 in the core region that is up doped by the up dopant (i.e., GE). Further, the

curve 302 transitions from the core region to the trench region which is down doped with

the down dopant (i.e., F) such that the curve 302 dips in the trench region (i.e., the region

defined by R2 - R1). Specifically, the curve 302 illustrates that a value of the refractive

index A2 is minimum at an inner cladding dip point 306 in the trench region that is down

doped by the down dopant (i.e., F). The curve 302 further transitions from the trench

region to the outer cladding region (i.e., the region defined by R3 - R2) defined by the

outer cladding 110 that is undoped such that the curve 302 peaks to an outer cladding

peak 308a at an inner cladding outer cladding interface 308b that is lesser than the core

peak 304.

[0098] The graph 300 further has a straight line 310 that defines the relative refractive

index of the pure silica. The curve 302 transitions from the trench region to the outer

cladding region defined by the outer cladding 110 and follows the straight line 310 which

is due to the fact the outer cladding 110 is undoped. The outer cladding 110 has traces

of the down dopant that is near the inner cladding-outer cladding interface 308b.

Preferably, the traces of the down dopant near the near the inner cladding-outer cladding

interface 308b is negligible.

[0099] Fig. 3B is an enlarged sectional view of the graph 300 illustrating a RI profile of the

core 102 of the optical fiber 100 with the outer cladding 110 being undoped. The core

102 defines the core region such that the refractive index Al of the core 102 is realized

in the core region (i.e., within the radius R1 of the core 102). Moreover, the curve 302

illustrates that the value of the refractive index Al is maximum at the core peak 304 in

the core region that is up doped by the up dopant (i.e., GE).

[001001Fig. 3C is another enlarged sectional view of the graph 300 illustrating a RI profile

of the inner cladding 108 of the optical fiber 100 with the outer cladding 110 being undoped. The inner cladding 108 (i.e., the trench layer 108a) defines the trench region such that the refractive index A2 of the inner cladding 108 (i.e., the trench layer 108a) is realized in the trench region (i.e., within the radius R2 of the inner cladding 108). The deeper end of the inner cladding 108 at the intersection of the core 102 and the inner cladding 108 form a trench layer 108a that has a non-step single trench shape as illustrated by the curve 302. The non-step single trench shape is preferred over stepped trench because manufacturing process of the optical fiber with non-step trench is less complex and less time consuming as compared to the manufacturing process of the optical fiber comprising stepped trench. Moreover, the curve 302 transitions from the core region to the trench region which is down doped with the down dopant (i.e., F) such that the curve 302 dips in the trench region (i.e., the region defined by R2 - R1). Further, the curve 302 illustrates that the value of the refractive index A2 is minimum at the inner cladding dip point 306 in the trench region that is down doped by the down dopant (i.e.,

F). The non-step trench shape of the trench layer 108a comprising only one dip point

306.

[00101] Fig. 3D is yet another enlarged sectional view of the graph 300 representing a RI

profile of the outer cladding 110 of the optical fiber 100 with the outer cladding 110 being

undoped. The outer cladding 110 define the outer cladding region such that the refractive

index A3 of the outer cladding 110 is realized in the outer cladding region (i.e., within the

radius R3 of the outer cladding 110). Further, the curve 302 transitions from the trench

region to the outer cladding region (i.e., the region defined by R3 - R2) defined by the

outer cladding 110 that is undoped such that the curve 302 peaks to the outer cladding

peak 308a at the inner cladding outer cladding interface 308b that is lesser than the core

peak 304. Furthermore, the graph 300 has the straight line 310 that defines the relative

refractive index of the pure silica. The curve 302 transitions from the trench region to the outer cladding region defined by the outer cladding 110 and follows the straight line 310 which is due to the fact the outer cladding 110 is undoped.

[00102] Fig. 3E is yet another enlarged sectional view of the graph 300 representing a RI

profile of the inner cladding-outer cladding interface 308a of the optical fiber 100 with the

outer cladding 110 being undoped. The curve 302 further transitions from the trench

region to the outer cladding region (i.e., the region defined by R3 - R2) defined by the

outer cladding 110 that is undoped such that the curve 302 peaks to the outer cladding

peak 308a at the inner cladding outer cladding interface 308b that is lesser than the core

peak 304. Moreover, the graph 300 further has the straight line 310 that defines the

relative refractive index of the pure silica. Further, the curve 302 transitions from the

trench region to the outer cladding region defined by the outer cladding 110 and follows

the straight line 310 which is due to the fact the outer cladding 110 is undoped.

[00103] Advantageously, the present disclosure provides an optical fiber 100 with a

fluorine doped cladding (i.e., the inner cladding 108) adjacent to the core 102 that brings

G654E and G654C properties in the optical fiber 100. Moreover, the optical fiber 100

with an immediate inner cladding 108 that is down doped with fluorine induce G654E

and G654C category optical fiber properties in the optical fiber 100 with predefined core

volume and trench volume thus providing good confinement and improved bending loss.

[00104] The foregoing descriptions of specific embodiments of the present technology

have been presented for purposes of illustration and description. They are not intended

to be exhaustive or to limit the present technology to the precise forms disclosed, and

obviously many modifications and variations are possible in light of the above teaching.

The embodiments were chosen and described in order to best explain the principles of

the present technology and its practical application, to thereby enable others skilled in

the art to best utilize the present technology and various embodiments with various

modifications as are suited to the particular use contemplated. It is understood that various omissions and substitutions of equivalents are contemplated as circumstance suggest or render expedient, but such are intended to cover the application or implementation without departing from the spirit or scope of the claims of the present technology.

[00105] In a case that no conflict occurs, the embodiments in the present disclosure and

the features in the embodiments is mutually combined. The foregoing descriptions are

merely specific implementations of the present disclosure, but are not intended to limit

the protection scope of the present disclosure. Any variation or replacement readily

figured out by a person skilled in the art within the technical scope disclosed in the

present disclosure shall fall within the protection scope of the present disclosure.

Therefore, the protection scope of the present disclosure shall be subject to the

protection scope of the claims.

Claims (15)

CLAIMS:

1. An optical fiber, comprising:

a core that is up doped with an up dopant; and

a cladding having inner and outer claddings, wherein the inner cladding is

down doped with a down dopant and is disposed adjacent to the core and the

outer cladding is at least one of: undoped and down doped, wherein the up dopant

is Germanium (Ge), wherein the optical fiber has (i) a Mode Field Diameter (MFD)

in a range of 9.5 pm to 13.0 pm and (ii) a Cable Cut off of less than 1530 nm.

2. The optical fiber as claimed in claim 1, wherein the core has a core radius in a

range of 4.5 micrometres (pm) to 6.5 pm, the inner cladding has an inner cladding

radius in a range of 22 pm to 25 pm, and the outer cladding has an outer cladding

radius in a range of 62.15 pm to 62.85 pm.

3. The optical fiber as claimed in claim 1, wherein the outer cladding has traces of

down dopant near an inner cladding-outer cladding interface.

4. The optical fiber as claimed in claim 1, wherein the core has traces of the down

dopant in concentrations less than 2500 parts per million (ppm).

5. The optical fiber as claimed in claim 4, wherein the down dopant is at least one of

Chlorine (Cl) and Fluorine (F).

6. The optical fiber as claimed in claim 1, wherein the outer cladding is made of pure

silica.

7. The optical fiber as claimed in claim 1, wherein the inner cladding has a trench

layer defined by a non-step single trench shape.

8. The optical fiber as claimed in claim 1, wherein an end of the inner cladding

adjacent to the core is deeper than an end of the core adjacent to the inner

cladding in the trench layer.

9. The optical fiber as claimed in claim 1, wherein the inner cladding has a trench

delta in a range of 0.22% to 0.32%.

10.The optical fiber as claimed in claim 1, wherein an attenuation of the optical fiber

is less than 0.17 dB/KM.

11.The optical fiber as claimed in claim 1, wherein a ratio of the core volume to the

trench volume is in a range of 0.082 to 0.11.

12.The optical fiber as claimed in claim 1, wherein, at least one of, (i) the core has a

core volume in a range of 5% pm 2 to 5.5% pm 2, and (ii) the trench layer has a

trench volume in a range of 48% pm 2 to 55% pm 2 .

13. The optical fiber as claimed in claim 1, wherein a total profile volume of the optical

fiber is in a range of 50% pm 2 to 60.50% pm 2 .

14.The optical fiber as claimed in claim 1, wherein when the outer cladding is

undoped, macro bend loss of the optical fiber at a wavelength of 1625 nm, a bend

diameter of 60 millimeters (mm), 100 turns of the optical fiber is less than 0.5

Decibel (dB).

15. The optical fiber as claimed in claim 1, wherein when the outer cladding is down

doped, a macro bend loss of the optical fiber at a wavelength of 1625 nm, a bend

diameter of 60 mm, 100 turns of the optical fiber is less than 0.1 dB.